Automatic control device for centerless grinding machine



w m m Q m M M Q )mw w w J m m 5 A 0 R I mm M o M QN a O ww m S k\ Q W may 1 \w s m R W M A Sept. 26, 1961 AUTOMATIC CONTROL DEVICE FOR CENTERLESS GRINDING MACHINE United States Patent T 3,001,336 AUTOMATIC CONTROL DEVICE FOR CENTER- LESS GRINDING MACHINE Alfred Ernst Richard Emil Bauer, Berlin-Mariendorf,

Germany, assignor to Aktiebolaget Malcus Holmquist,

a corporation of Sweden Filed Mar. 9, 1960, Ser. No. 13,784

3 Claims. (Cl. 51-103) The present invention relates to a device for the automatic control of the distance between the grinding wheel and the counter support roller in a centerless grinding machine of the type in which the work pieces are fed successively and substantially parallel to the axis of the grinding wheel, which device is operatively connected, through electric contacts and relays, to a gauging device for measuring the diameter of the ground work pieces. The gauging device is disposed after the grinding wheel, as seen in the direction of feed of the work pieces, and is adapted to check the diameter of the work pieces with regard to allowable maximum and sizes.

This application is a continuation-in-part of my prior copending application Serial No. 662,724 filed on May 31, 1957, now abandoned.

In grinding, in centerless grinding machines, the diameter of the work pieces is checked by means of a gauging device when the pieces have left the grinding area. If the diameter is too large, the distance between the grinding wheel and the counter support roller must be reduced; if, on the other hand, it is too small, said distance must be Patented Sept. 26, .1961;

ling device is interrupted by the switch each time bev elled ends of the work pieces pass the gaugingdevrce.

The consecutive work pieces 2 provided with bevelled ends 1 are fed in the direction as indicated by the arrow between the grinding wheel 3 and the counter support roller (not shown) and then to a gauging device 4. The latter, known per se and fitted in a known manner with sensing points or sensing tips, includes a dial gauge indi cator 5 which is capable of emitting electric operating impulses. For this purpose the dial gauge 5 is fitted with two adjustable contacts 6 A and 7 between which the pointer 9, oscillates, said pointer being normally in the position shown and having a contact 8;

After the gauging device 4 a switch 10 is cutin which only transmits the operating impulses from the dial-gauge 5 when the switch is closed, that-is, only when the bov engages that work piece 2 which is supposed to leave the increased. In the first mentioned instance one speaks of a positive correction and, in the last mentioned instance, of a negative correction.

The present invention concerns itself, more particularly, with work pieces whose main body portions have the desired or correct sizes which must not be changed except, of course, where an actual error, either positive or negative, occurs on these main body portions; in addition these work pieces are characterized in that (1) they are bevelled at their ends and thus have a decreasing diameter at these points, or (2.) they have end faces which are not at right angles to the central axis, or (3) they might be provided with steps at or intermediate their ends, the diameter of the steps being less than that of the main body portions of the work pieces. When work pieces of the above type, which are continuously fed during the grinding operation, pass the gauging device, a negative correction would ordinarily be called for when the ganging device comes in contact with these bevelled or stepped portions of reduced diameter. However, a correction of this kind must be prevented if the diameter of the intermediate or main body portions of the work pieces has the desired or correct size.

According to the invention, a switch is connected for this purpose between the gauging device and the controlling device, which switch is capable of being directly or indirectly actuated by the work piece which is in the gauging device or, as viewed in the direction of feed of the work pieces, ahead of or after said gauging device; the actuation being effected in such a manner that the connection between the gauging device and the controlling device is automatically interrupted when a groove or shoulder of a work piece or the gap between two work pieces is between the sensing point of the gauging device, whereby the gauging device is not then permitted to aflect the controlling device.

The invention and its various features will be disclosed more in detail in the following in connection with a description of an embodiment illustrated schematically in the accompanying drawing and according to which the connection between the gauging device and the controlelled ends 1 of the work pieces are not between the sonsing points of'the gauging device 4. The switch 10 is closed by means of a knee level-11 which maintains the switch closed as long as the freeend of the lever *11 grinding machine, whilst the switch 10 opens as soon s the work piece 2. leaves the grinding machine. For this purpose the switch 10 with the knee lever 11 is disposed at such a distance, from the gauging device 4 that the work piece 2' leaves the grinding machine and opens the switch 10 at that moment when thebevelled ends lot the work pieces are between the sensing points of the gauging dey vice'4... V s i In the drawing the switch 10 is shown in the position where the work piece 2. is just about to close the same. Hence, the switch 10 is opened and closed alternatelyby each work piece.

If the smallest diameter of the work piece ends lies within the permissible range of dimension which is defined by the mutual distance of the contacts 6 and 7, no correctionis performed of the distance between the rinding wheel and the counter support roller when the ends are passing through the gauging device 4, and this will be independent of whether the switch 10 is closed or not as the pointer contact 8 never touches the contact 6 intended for negative corrections.

If the smallest diameter of the ends 1 of the work piece lies below the permissible range of dimensions, the pointer 9 is compelled to move, when the ends are between the sensing points of the gauging device 4, to the position where the pointer contact 8 touch-es the contact 6; no correction being performed, however, as the switch 10 is then open. d

The relay set 12, which affects the controlling device, is shown diagrammatically in the drawing, the same being connected to a battery which is also shown diagrammatically. The operation of the relay set 12 will be described hereinafter. 7

If a negative or positive correction is to be performed,

this can take place only when the switch 10 is closed and the pointer contact 8 touches the contact 6 or 7, as stated above.

The controlling device consists chiefly of a magnet 13 for negative corrections and a magnet 14 for positive corrections'. If the magnet 13 is energized through the relay set 12, the shaft 17 of a ratchet wheel 16 is turned in the direction as indicated by the arrow 18 by means of a lever and pawl mechanism 15- and the ratchet wheel 16, and by this action the distance between the grinding wheel and the counter support roller is increased. (The rotary movement of the shaft 17 will adjust the position of the counter support roller.) If the magnet 14 is energized through the relay set 12 for the purpose of obtaining a positive correction, the shaft 17 is turned in the direction as indicated by the arrow 20 by means of a lever and pawl mechanism 19 and the ratchet wheel 16, whereby the distance between the grinding wheel and the counter support roller is decreased.

As shown in the drawing; the relay set 12 is connected to a source of electric power, such as a battery. The pointer: 9 ,is connected by means of lead 21, through an internal connection in the relay set'12, to lead 22 connecting with one of the contacts of switch 10. The other contact ofswitch 10 is connected by means of lead 23, through an internal connection in the relay set 12, to the positive terminal 240f the battery. Thus, the switch 10 is in series between the positive terminal of the battery andthe pointer 9. Contact 6 is connected by means of lead 25, through an internal connection in the relay set between the grinding wheel and the counter support roll- 12, to lead 26 connecting with the upper portion of the I magnet 13, -Contact 7 is connected by means of lead 27, through an internal contact in the relay set 12, to lead 28 connecting with the upper portionot the magnet 14. {The lower'portions of "the magnets 13 and 14 are connected by means of common lead 29, which, in turn, is connected through an internal connection in the relay set '12- to the negative terminal 30 of the battery. Thus, the electrical connections illustrated herein are consistcut with the above explanation relative to the operation of the controlling device.

Q The relay set 12 contains a counter (not shown) which is radapted to count the number of work pieces passing beyond thegrinding wheel 3 and the gauging device 4 and which is adjustable in correspondence with this number of work pieces in such a way' that the counter is driven on one step at a time by the switch 10 every-time the svvitch'is opened iand closed'; andin attaining the number of-work pieces "setfth'e counter permits the oper in a centerless grinding machine of the type in which work pieces are fed in succession past the grinding Wheel and substantially parallel to the axis thereof, and wherein a gauging device disposed after the grinding wheel measures the diameter of each ground work piece in succession and, through a suitable electrical circuit between said gauging device and said controlling device, auto matically changes the distance between the grinding wheel and the counter support as the measured diameter varies from a predetermined value, the improvement which comprises a switch disposed after the grinding wheel and actuated byone of the work pieces for interrupting the circuit "between the gauging device andthe automatic controlling device whenever a gap between two work pieces occurs at the gauging device and whenever a gap or shoulder in a work piece passes the gauging device.

2. The mechanism accordingf to claim 1, including a lever pivotally mounted adjacent the line of feed of said work pieces, one end of said lever contacting the work pieces individually as they pass, and the other end of said lever operating said switch, whereby, as a work piece passesbeyond said lever, said switch will be closed when said one end of said lever is contacting the normal porcrating impulse from thedial gauge 5 to be transmitted to the controlling device. i I As will be appreciated, the device is applicable in the same manner it the work-pieces have end faces oblique to the center axis instead of havingbevelled ends, or if the work pieces present the above mentioned steps at the ends or within the surface to be ground, respectively. 1

What is claimed is: V

' 1. In a device for automatically controlling the distance tion of said work piece, and whereby when said one end of said levercontacts a bevelled portion of said work piece or gap between adjacent work pieces said switch will be open.

3. The mechanism according to claim 1, wherein said switch is located beyond said gauging device, in the-direc tion of-feed, whereby said switch is actuated by those pieces which are leaving the terminal end of the grinding machine.

References Cited in the file of this patent UNITED STATES PATENTS 2,486,950 Jagan Nov. 1, 1949 2,718,100 Hjarpe Sept. 20, 1955 2,795,088 Schouhoft June 11, 1957 Burridge May 26, 1959 

